Insights into the late-stage differentiation processes of the Catalão I carbonatite complex in Brazil: New Sr–Nd and C–O isotopic data in minerals from niobium ores

Oliveira, Ítalo Lopes de; Brod, José Affonso; Cordeiro, Pedro; Dantas, Elton Luiz; Mancini, L.

doi:10.1016/j.lithos.2016.12.034

Cited by 10 publications

(4 citation statements)

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“…The position of pits, rivers and towns are also highlighted for reference. Maps redrawn from Vartiainen and Paarma (1979), Vartiainen et al (1990) [Sokli]; Ivanyuk et al (2002), Mikhailova et al (2016) [Kovdor]; Davies (1947), Baldock (1971 [Bukusu]; Verwoerd (1967) [Glenover]; and Oliveira et al (2017) [Catalão]. Geological maps are projected using an auxiliary sphere Mercator projection, WGS1984 geoid.…”

Section: Introductionmentioning

confidence: 99%

The origin and composition of carbonatite-derived carbonate-bearing fluorapatite deposits

et al. 2020

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Carbonate-bearing fluorapatite rocks occur at over 30 globally distributed carbonatite complexes and represent a substantial potential supply of phosphorus for the fertiliser industry. However, the process(es) involved in forming carbonate-bearing fluorapatite at some carbonatites remain equivocal, with both hydrothermal and weathering mechanisms inferred. In this contribution, we compare the paragenesis and trace element contents of carbonate-bearing fluorapatite rocks from the Kovdor, Sokli, Bukusu, Catalão I and Glenover carbonatites in order to further understand their origin, as well as to comment upon the concentration of elements that may be deleterious to fertiliser production. The paragenesis of apatite from each deposit is broadly equivalent, comprising residual magmatic grains overgrown by several different stages of carbonate-bearing fluorapatite. The first forms epitactic overgrowths on residual magmatic grains, followed by the formation of massive apatite which, in turn, is cross-cut by late euhedral and colloform apatite generations. Compositionally, the paragenetic sequence corresponds to a substantial decrease in the concentration of rare earth elements (REE), Sr, Na and Th, with an increase in U and Cd. The carbonate-bearing fluorapatite exhibits a negative Ce anomaly, attributed to oxic conditions in a surficial environment and, in combination with the textural and compositional commonality, supports a weathering origin for these rocks. Carbonate-bearing fluorapatite has Th contents which are several orders of magnitude lower than magmatic apatite grains, potentially making such apatite a more environmentally attractive feedstock for the fertiliser industry. Uranium and cadmium contents are higher in carbonate-bearing fluorapatite than magmatic carbonatite apatite, but are much lower than most marine phosphorites.

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Section: Introductionmentioning

confidence: 99%

The origin and composition of carbonatite-derived carbonate-bearing fluorapatite deposits

et al. 2020

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“…on considerations by Speziale et al (1997) and CominChiaramonti et al (2005b (Cordeiro et al 2011, Oliveira et al 2017). There, the original isotopic composition of carbonates was modified by at least two events of magmatic fractionation (1 -Rayleigh fractionation, with carbonate signatures being related to the isotopic fractionation between carbonates and other minerals as well as to the temperature and the isotopic composition of the initial melt, and 2 -degassing) and three fluid fractionation (fluid degassing, H 2 O percolation and CO 2 -H 2 O fluid percolation) episodes.…”

Section: Comin-chiaramonti Et Al (2005c)mentioning

confidence: 92%

“…The most important mineral ores are represented by miaskitic alkaline complexes with syenites + pyroxenites + ijolites + carbonatites, and/or their effusive equivalents as main petrographic types. Recently, Oliveira et al (2017) observed that the distinct evolution trends reaching late-stage rocks from Catalão I coincide with a shift from a Nb-rich to a REE-and Ba-rich mineralization environment.…”

Section: Economic Aspectsmentioning

confidence: 99%

Cretaceous carbonatites of the southeastern Brazilian Platform: a review

et al. 2018

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“…849 Figure 1. Geological maps of (a) the Araxa carbonatite complex and (b) the Catalao I carbonatite 850 complex modified from Traversa et al (2001) and Oliveira et al (2017), respectively. 851 Figure 2.…”

Section: Figure Captionsmentioning

confidence: 99%

Niobium, Critical Metal, and Progeny of the Mantle

Williams‐Jones

Vasyukova

2023

Economic Geology

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Niobium is a critical metal in high demand because of technological advances and the supply risk created by the fact that over 90% of its production is by a single country (Brazil). In this paper, we review the geology of the deposits that are currently being mined and other potentially economic deposits as well as develop models for their genesis. With the exception of the Lovozero deposit (Russia), which is hosted by a layered silica-undersaturated alkaline igneous complex, all the deposits that are currently being mined for niobium are hosted by carbonatites, and most of the deposits with economic potential are also hosted by these rocks. Niobium owes its concentration in carbonatites and alkaline silicate rocks to its highly incompatible nature and the small degree of partial melting of the mantle required to generate the corresponding magmas. The primary control on the concentration of niobium to economic levels in alkaline silicate magmas is fractional crystallization, partly prior to but mainly after emplacement. In the case of silica-undersaturated magmas, the final residue saturates in minerals like eudialyte and loparite to form niobium-rich horizons in the layered complexes that crystallize from these magmas. The final residue, in the case of silica-saturated magmas, crystallizes the pegmatites that are the hosts to the economic niobium mineralization, which commonly takes the form of pyrochlore. In contrast, carbonatitic magmas undergo little to no fractional crystallization prior to emplacement. Moreover, fractional crystallization on emplacement has minimal impact on the concentration of niobium to economic levels. Instead, we propose that the metasomatic interaction of the carbonatitic magmas with their hosts to form rocks like phlogopitite (glimmerite) consumes much of the magma, leaving behind a phoscoritic residue from which pyrochlore crystallizes in amounts sufficient to form economic deposits. Although many niobium deposits display evidence of intense hydrothermal alteration, during which there can be major changes in the niobium mineralogy, the extremely low solubility of niobium in aqueous fluids at elevated temperature precludes significant mobilization and, thus, enrichment of the metal by hydrothermal fluids. However, weathering of carbonatite-hosted niobium deposits leads to supergene enrichment (due largely to the dissolution of the carbonate minerals) that can double the niobium grade and make subeconomic deposits economic. Pyrochlore is the principal niobium mineral in these laterite-hosted deposits, although its composition differs considerably from that in the primary mineralization. This paper evaluates the processes that appear to be responsible for the genesis of niobium ores and provides a framework that we hope will guide future in-depth studies of niobium deposits and lead to more effective strategies for their successful exploration and exploitation.

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Insights into the late-stage differentiation processes of the Catalão I carbonatite complex in Brazil: New Sr–Nd and C–O isotopic data in minerals from niobium ores

Cited by 10 publications

References 45 publications

The origin and composition of carbonatite-derived carbonate-bearing fluorapatite deposits

The origin and composition of carbonatite-derived carbonate-bearing fluorapatite deposits

Cretaceous carbonatites of the southeastern Brazilian Platform: a review

Niobium, Critical Metal, and Progeny of the Mantle

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